Air lock for a powder cooler



J. P. TERRETT AIR LOCK FOR POWDER COOLER June 9, 1959 v 2 Sheets-Sheet l Filed Nov. 25, 1957 INVENTOR. JOHN I? TEE/P577 June' 9, 1959 J. P. TERREILT AIR LOCK FOR A POWDER COOLER I 2 Sheets-Sheet 2 Filed Nov. 25, 1957 INVENTOR. JOHN P TERRETT M ATTORNEYS Patented June 9, 1959 AIR LOCK FOR A POWDER COOLER John P. Terrett, Detroit, Mich assignor to C. E. Rogers Company, a corporation Application November 25, 1957, Serial No. 698,826

2 Claims. (Cl. 302-59) operation without clogging or plugging is likewise im-- portant.

' It is therefore an object of my invention to provide air lock which will permit the discharge of the powdered product during the course of production of the material. It is another object of the invention to provide such a device which is readily maintained in a sanitary con dition and which can easily be substituted or cleaned.

Another object of the invention is to provide such a In such manufacture the original a readily removable flange clamp 12, is an air lock mechanism 13. This includes a number of parts arranged in line or in series on a vertical axis 14 coincident with the vertical axis of the separator 8. The top element is a conduit section 16 directly secured in position for ready removal by the spring clamp 12. The lower portion of the section 16 has an integral, outturned flange 17 matched by a similar flange 18 on the next lower adjacent tube section 19. The sections 16 and 19 are held together by readily removable and suitable fasteners 21. The flanges 17 and 18 clamp in position an upper sleeve 22.

The sleeve serves as a valve and is generally made of rubber. This term is intended to include any rubberlike flexible material, whether natural or synthetic and having the properties of being substantially air tight and quite yieldable or flexible. The material should also be capable of being cleaned easily and of being nondevice which is mechanically simple and straight-forward in order that jamming or clogging will not occur.

A further object of the invention is to provide a 1913."-

tively inexpensive, cheap, and durable air lock device.

A still further object of the invention is to provide an .air lock device which can be utilized with machines already in use and which then require but little or no,

alteration.

Other objects, together with the foregoing, are attained embodiments of the invention described in the accompanying description and illustrated in the accompanying drawings in which:

Figure 1 is a diagrammatic side elevation of an air lock for a powder cooler constructed in accordance with my invention.

Figure 2 is a cross-section on a vertical axial plane through a portion of the structure of Figure l, the scale being enlarged.

Figure 3 is a cross-section the plane of which is indicated by the line 3-3 of Figure 2.

Figure 4 is a perspective of a portion of the air lock mechanism with the adjacent structure broken away.

Figure 5 is a cross-section through a modified form of the device installed in a different style of powder cooler.

Figure 6 is a cross-section the plane of which is indicated by the line 6-6 of Figure 5.

Although the air lock of the invention has a wide field of application it is described herein in connection with a cooler for use after the desiccation of milk powder, for example. The material when substantially dried and in powder form is carried by an air medium or air stream into a duct 7 leading into a cyclone separator 8. This is of substantially standard construction and has an outlet 9 to permit the egress of air separated from the incoming powder. The powder itself whirls around the inside of the separator and by gravity falls and is confined or converged by the conical wall 11 of the separator so that the powder tends to gravitate toward the bottom central portion of the separator.

Secured to the bottom of the separator, preferably by .40 in the embodiments of the invention described in the absorptive of or not detrimental to materials passing thereby.

The sleeve 22 at its upper end is stretched or deformed so as to lie between the flanges 17 and 18. When the fastenings 21 are tightened the sleeve 22 can be considered as having an integral rim 23 securely clamped to hold the sleeve in position. The part of the sleeve adjacent the rim 23 is substantially circular in crosssection since that is the cross-sectional contour of the duct sections 13 and 19. Adjacent its lower end, the sleeve 22 is not circular. Rather in cross-section it has the shape of a nearly flat ellipse. The sleeve can therefore be considered to have at its lower end a virtually straight lip 24 and a parallel lip 25. These are, When seen in end view, approximately rectilinear and extend diametrically across the duct section 19. When they are not under stress of any sort the lips 24 and 25 do not quite meet, but preferably have a slight gap to permit some flow. Between the relatively straight diametrical lips 24 and 25 at the bottom and the circular top, the sleeve shape varies gradually and smoothly without any abrupt changes. In cross-section in an axial plane as in the plane of Figure 2 the sleeve appears to be approximately conical whereas in cross-section in an axial plane at 90 thereto the sleeve appears to be approximately rectangular.

. Similarly, the pipe section 19 at its lower end is provided with a flange 27 matching a flange 28 on a still lower conduit section 29. Fastenings 31 secure the sections 19 and 29 together and likewise clamp between them the outturned rim 32 of a rubber-like sleeve 33. This is identical with the sleeve 22 except that in most installations it is somewhat shorter and is made of material somewhat heavier in cross-section. The lips 34 and 36 at the bottom of the sleeve 33 are slightly apart in most embodiments when they are unstressed. Secured to the lower section 29 is a terminal unit 37 having fastenings 38 for ready removal.

In the operation of this device, the terminal unit 37 usually operates substantially at atmospheric pressure whereas inside the separator 8 the pressure is usually somewhat less than atmospheric. There is thus a slight vacuum on both of the sleeves 22 and 33. When the separator 8 is empty for example, the lips 24 and 25 as well as the lips 34 and 36 are slightly stressed and so are brought together to prevent the ingress of outside air.

When the first portion of powder comes into the separator 8, it gravitates to the bottom thereof and passes through the section 13. The powder falls by gravity into the sleeve 22 and since it has substantial weight deforms or deflects the material of the sleeve 22 and passes freely into the interior of the lower sleeve 33. If this is a small batch of powder, insufficient to fill the interior of the sleeve 33, the lips 24 and 25 return to their former nearly closed position. Subsequent powder entering the sleeve 22 repeats the previous operation until such timeas the sleeve is substantially full or is loaded above the bottom of the lips 24 and 25. condition is approximately illustrated in Figure 2'. When the "weight of the material in the lower sleeve 33 is sulfic'ient, it overcomes the somewhat stifier material of that sleeve and opens the lips 34 and 36- a substantial amount thus permitting the load within the sleeve 33 to fall by gravity into the outlet section 37. During this time, if there is a substantial increase of pressure within the sleeve 33 as compared tothat within the sleeve 22, the lips 24 and 25 substantially close thus preventing an inrush of air into the partially evacuated separator 8.

The foregoing operation continues with the powdered material exiting either at short intervals or almost continuously. When the last of the material has passed, the lower pressure within the chamber 8 causes the lips 34 and 36 substantially to close and the lips 24 and 25 substa'nt-ially to close so that there is no excessive ingress of air, but so that the pressure within the sleeves 22 and 33 is about equalized.

This mechanism can be periodically disassembled and removed for thorough cleaning, all surfaces being immediately available. The rubber-like sleeves can be replaced or simply cleaned and" reused. In the event one of them is damaged in any way it can readily be replaced at a low cost.

While two sleeves such as 22 and 33: are preferably used in most installations, it is possible under certain special conditions to utilize but a single sleeve. This may result in slightly more ingress of air during discharge and may permit some further loss of vacuum in the event the single sleeve is destroyed or torn. Operation in practice has given better experience with two sleeves as shown.

in some instances the powder cooler does not operate entirely in a vertical direction and the powder is received in the bottom of a chamber 41 (Figure from which it does not flow by gravity. The chamber 41 is provided with an outlet elbow 42 leading to a vertical discharge duct 43 and also is provided with a screw conveyor 44 mounted on a shaft 46 extending through the elbow 42 and journalled in a bearing 47.

The elbow 42 terminates in a flange 48 secured to the chamber 41 by fastenings 49. This affords a convenient means for clamping the rim of a rubber-like deformable sleeve 51 comparable in substantially all respects to the sleeves 22 and 33. This sleeve upon installation is deformedto provide a rim 52 extending between the flange 48 and the main body of the chamber 41. At that upstream location the sleeve is substantially circular in cross-section. The other, downstream end of the sleeve is a flattened ellipse (Figure 6) extending substantially diametrically across the outlet elbow 4-2. In the central portion of the downstream end of the sleeve, the lips 53 and 54 are distorted to lie around and closely encompass the shaft 46. There are slight openings where the sleeve does not quite fit the shaft.

In the operation of this mechanism, powder advanced by the screw 44 toward the outlet elbow 42 is pressed through the sleeve 51. The lips 53 and 54 necessarily open to permit the powder to pass. falls by gravity through the outlet 43 and is discharged. When powder is not passing into the elbow 42 and the sleeve 51 is no longer stressed, the rubber-like material of the sleeve returns substantially to the position shown in Figure 6 in fairly tight engagement with the shaft 46 so that there is substantially no leakage and the vacuum within the chamber 41 is preserved. Turning of the shaft 46' within the rubber-like material of the sleeve does not cause any particular wear or do any harm. A relatively tight fit is maintained over a protracted period of operation. The elbow 42 can readily be removed and the sleeve 51 can then be removed and replaced or can be cleaned.

What is claimed is:

1. An air lock for a powder cooler comprising a chamber, an outlet duct at the bottom of said chamber, means for introducing powder to said chamber for gravitation toward said outlet duct, and a pair of rubber sleeves arranged one above the other in said outlet duct, each of said sleeves having a rim making a tight engagement with the wall of said outlet duct and having lips slightly open when unstressed and disposed below said rim and extend in'g substantially diameterically of said outlet duct, the lips of said upper sleeve being below the rim of said lower sleeve.

2. An air lock for a powder cooler comprising a chamber, an outlet duct at the bottom of said chamber, means for conducting powder in said chamber toward said outlet duct, and a rubber sleeve arranged in said outlet duct, said sleeve having a rim in tight engagement with the walls of said outlet duct, and having lips slightly open when unstressed and disposed below said rim and extendin'g substantially diametrically of said outlet duct.

References Cited in the file of this patent UNITED STATES PATENTS 488,160 Buhrman Dec. 13, 1892 2,035,410 Smith Mar. 24, 1936 2,352,642 Langdon July 4, 1944' 2,355,774 Baker Aug. 15, 1944 2,428,995 Rogers Oct. 14, 1947' 2,474,205 Welty June 21, 1949 2,489,980 Rogers Nov. 29, 1949 This powder then 

